Hematocrit corrected glucose measurements using phase angles and impedance for electrochemical test strip

A method to determine analyte concentration in a blood sample, the method comprising:

• depositing a blood sample in a test chamber of a test strip having at least first and second electrodes in contact with a reagent and third and fourth electrodes not in contact with the reagent;
• driving a non-oscillating signal to the at least first and second electrodes to cause a reaction with the glucose in the blood sample and the reagent;
• measuring a current output of the reaction to establish a preliminary analyte concentration;
• applying a first oscillating input signal at a first frequency to third and fourth electrodes;
• determining a first estimated hematocrit based on a impedance from output signals of the third and fourth electrodes;
• applying a second oscillating input signal at a second frequency higher than the first frequency to the third and fourth electrodes;
• ascertaining a second estimated hematocrit based on a phase angle of output signals from the third and fourth electrodes;
• estimating a hematocrit of the blood sample based on the first and second estimated hematocrits;
• and
• deriving a final analyte concentration based on the preliminary analyte concentration and the hematocrit from the estimating step.